In generic vehicles, such image processing systems are used for various applications in which several cameras are employed simultaneously. Such applications can for example include side-view, lane detection, parking camera and interior camera for monitoring by the driver. Moreover, it can be sensible to simultaneously present, on the image display unit, the information from several cameras.
The image data sources of these image processing systems are often designed in the form of CCD chips and/or CMOS chips. Fundamentally, the light-sensitive cells of these chips only acquire color-independent brightness values. In order to obtain color information a color filter in one of the primary colors of the respective color system, for example in red, green or blue, is placed in front of each individual cell. In such an arrangement, the filters are for example affixed to the cells in an arrangement which is referred to as a “Bayer pattern”. In this arrangement, the first line of the light-sensitive cells comprises filters in the order of red, green, red, green etc.; the second line comprises filters alternately colored green, blue, green, blue etc.; and the third line again comprises filters alternately colored red, green, red, green etc. As a result of these filters being in place, each of the cells only measures the brightness of the individual color components and conveys said brightness as pixel data.
At first, this pixel data cannot be displayed on the image display unit. The adjacent cells have to be used in order to detect the true color. This color interpolation is undertaken by means of a conversion unit. As a result, the conversion unit provides image data which can be presented on the image display unit.
In order to achieve simultaneous display of the information from several image data sources, it is necessary to bring the image data from several image data sources together. Such bringing together takes place by means of a mixing unit. In the state of the art, conversion of the pixel data to image data is always carried out first, followed by the bringing together of the image data for simultaneous display on the image display unit.
This embodiment has a disadvantage in that in each case the pixel data of the image data sources first has to be transformed to image data, wherein such transformation is carried out in a conversion unit. This necessitates many of these conversion units, which results in very considerable expense.
This embodiment is associated with a further disadvantage in that during color interpolation even those image regions are calculated which for example as a result of overlay of additional information on the image display unit, or as a result of overlap in the image sections of different image data sources, will never be displayed on the image display unit. This type of image processing unnecessarily uses resources in the time intensive interpolation process, and/or slows down the interpolation process.